Imported Upstream version 3.6.0

Former-commit-id: da6be194a6b1221998fc28233f2503bd61dd9d14

mcs/errors/cs4027.cs

@@ -0,0 +1,35 @@
+// CS4027: The awaiter type `A' must implement interface `System.Runtime.CompilerServices.INotifyCompletion'
+// Line: 33
+
+using System.Threading.Tasks;
+
+static class S
+{
+	public static A GetAwaiter (this int i)
+	{
+		return new A ();
+	}
+}
+
+class A
+{
+	bool IsCompleted {
+		get {
+			return true;
+		}
+	}
+	
+	public void OnCompleted (System.Action a)
+	{
+	}
+
+	int GetResult ()
+	{
+		return 3;
+	}
+	
+	static async Task<int> Test1 ()
+	{
+		await 1;
+	}
+}